Snapshot A 33-year-old man presents to his primary care physician for a rash involving his left leg. His symptoms began approximately 7 days ago, when he noted a rash. He is unsure if he had any trauma to the leg but states he has had mild fevers. The patient is allergic to penicillin. His temperature is 100°F (37.7°C), blood pressure is 138/88 mmHg, pulse is 98/min, and respirations are 18/min. Physical examination is notable for an erythematous, edematous, and warm lesion involving the left ankle that is tender to palpation. He is started on clindamycin. (Cellulitis) Introduction Mechanism of action reversibly binds to the 50S ribosomal subunit, impairing bacterial protein synthesis impairs the transpeptidation reaction within the ribosome Clinical use anaerobic infections (e.g., aspiration pneumonia, oral infection, and lung abscess) Bacteroides spp. Clostridium perfringens Fusobacterium spp. staphylococci viridans group streptococci Streptococcus pyogenes Streptococcus pneumoniae group A streptococcal infection Adverse effects Clostridium difficile infection (pseudomembranous colitis) fever diarrhea